Research
Mixed
Cold exposure during sleep does not significantly disrupt sleep stages (SWS/REM) when bedding and clothing are used, but it significantly alters cardiac autonomic activity (increasing parasympathetic dominance) without affecting subjective sleep quality.
Even if you sleep well in a cold room, your heart is under stress. Cold exposure increases cardiac parasympathetic activity and blood pressure fluctuations during sleep, which may increase cardiovascular risk, especially in the elderly. Keep your bedroom temperature above 10°C and use adequate bedding to minimize this hidden stress.
GoodQualifiesHIGH confidence
In studies using clothing and/or bedding, no significant difference was observed in sleep... However, our study indicates that cold exposure significantly changes cardiac autonomic activity during sleep, without affecting the sleep stages.
Why this rating
Based on specific HRV studies cited in the review.
Source
Effects of thermal environment on sleep and circadian rhythm
Kazue Okamoto-Mizuno et al. · Journal of PHYSIOLOGICAL ANTHROPOLOGY · 2012
DOI 10.1186/1880-6805-31-14
narrative_reviewCited 450×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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